BirthFlow and FlowUpdate from MaxFluidLoader returns strange results
#1
Hi!

I created a little fluid sim with 3dsmax liquid and loaded it with the 3dsmax fluid loader object.

The sim looks fine in viewport, but when I feed it into a birth flow and a flow update operator, I receive strange results.

I attached 2 videos and an image. I also send you an email with a download link which contains a part of the simcache files and a maxfile.

Please have a look.


Thank you and greetings!

   


.mp4   MaxFluidsLook.mp4 (Size: 3.96 MB / Downloads: 47)

.mp4   BirthFlow_FlowUpdate_FromMaxFluids.mp4 (Size: 705.28 KB / Downloads: 32)
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#2
The cache you sent me does not seem to contain particle IDs, which are required for tracking within tyFlow. So either a) you forgot to export them, or b) max fluids particle loader doesn't expose them (and is therefore broken). I've never used max fluids so I can't tell which is the case...
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#3
I can't say much about the IDs. Maybe I have to investigate.
But I am confused by the point, that tyMesher can read the same fluid loader and mesh it perfectly fine. But BirthFlow can't handle it?

You can try it with the cache I sent you. Just create a tyMesher and pick the FluidLoader.
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#4
tyMesher isn't history dependent. tyFlow needs IDs to track which particles are which over time.
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#5
Okay, thank you for explaning this.
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#6
Hi!

Now on new tyFlow_016107 I get different results. Its getting better with the newly added feature "added “index is ID” settings to Birth Flow/Flow Update operators". Thanks for this!

The visual representation of the particles is now matching the FluidLoaders particles, which is good, but DisplayData operator shows strange results. It seems that the particles are unique by their index for each frame, but they don't have a constant ID which stays over time. Also I think the shown velocity vectors are very large.

Now my question is: Are the particles useful for further work with tyFlow, even if they aren't constantly trackable over time?

Here are some screenshots:
   
   
   
   

.mp4   tyFlow_MaxFluidLoader_DataTracking.mp4 (Size: 5.23 MB / Downloads: 34)
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#7
You are correct, because Max Fluids do not export the particles in order, their index is not consistent over time...so they constantly swap positions each frame. The current state of the Birth Flow/Flow Update operator is as far as I can push things...without a valid ID exported (or consistent particle ordering), there's no way I can track unordered particles for proper moblur/velocity and such.
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#8
Okay, big thanks for your efforts!

So now it's up to the max devs, wether they bring accessable constant IDs or not. We will see :-D!
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#9
(02-08-2021, 08:18 AM)tyFlow Wrote: ... , there's no way I can track unordered particles for proper moblur/velocity and such.

But isn't the velocity stored in the cached file sequence? Or do I miss something?
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#10
Hmm I guess technically yea, but if any processes are reliant on interpolating particle positions, they won't work correctly.
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#11
(02-08-2021, 03:43 PM)tyFlow Wrote: Hmm I guess technically yea, but if any processes are reliant on interpolating particle positions, they won't work correctly.

Thanks to the OP for posting this on the FaceBook group and bringing it to our attention -- I'm working on the ID and velocity fix now.

-Tom
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